The present invention relates to perforated filmstrip transport mechanisms in general, and to methods and apparatuses for consistently registering perforated filmstrip images in particular.
High speed perforated filmstrip transportation for such applications as scanning, recording and optical printing not only require reliable movement of filmstrips, but also consistent registration of the filmstrip images. That is, it is important that each image on a filmstrip come to momentary rest at the same location along the direction of travel, within an acceptable tolerance. When images are not properly registered, undesirable image artifacts can be produced, with the severity of the artifacts being more pronounced with film transport speed.
One basic prior art approach to filmstrip registration is to use sprocket teeth (or pins) that engage the perforations with an interference fit. Because the action of insertion or removal of the pins can lead to image artifacts due to film displacement, such approaches require pauses in the processes which may greatly limit the filmstrip transport speed. Additionally, minute, periodic and random variations induced in the film manufacturing processing can also lead to image artifacts.
Another basic prior art filmstrip registration approach partially addresses the problems associated with the aforementioned approach, by using precisely machined pins which have a smaller projected area than the perforation areas. Registration is accomplished by using the filmstrip tension to rest edges of the perforations against the corresponding edge of the pins. For example, the pins can be made to consistently rest against the trailing edges of all of the perforations. While this approach allows for a faster filmstrip transport speed, it does not address the problem of inconsistent registration (and the resulting artifacts) due to variability in the distances between the perforation distances.
What is therefore of great interestxe2x80x94but not provided for in the prior artxe2x80x94are a high speed filmstrip transport device and method which eliminates image artifacts caused by variations in relative perforation distances.
To address the unmet needs of the prior art identified supra, the present invention provides a filmstrip transport system adapted for perforated filmstrip transport and filmstrip image registration. The system at least includes a substrate adapted to apply a normal force to a filmstrip, and a plurality of registration-tension assemblies carried by the substrate, the registration-tension assemblies each at least including a registration pin member having a registration pin sized for a non-interference fit with filmstrip perforations and a tension pin member having a tension pin sized for a non-interference fit with filmstrip perforations.
The registration-tension assemblies have a registration mode to engage and register a filmstrip by resting an edge of one perforation of the filmstrip against the side of an inserted registration pin, and placing the filmstrip in tension by pulling the filmstrip via a tension pin inserted in another perforation in the filmstrip, in a direction substantially parallel to the direction of filmstrip transport and away from the registration pin. The registration-tension assemblies also have a load mode to load the registration and tension pins into prospective perforations by moving the tension pin in a direction substantially parallel to the direction of filmstrip transport and toward the registration pin until the registration and tension pins achieve a distance therebetween permitting a non-interference fit into two filmstrip perforations.
The present invention also provides a method of transporting and registering a filmstrip. The method at least includes the steps of, via a substrate, providing a normal force to a filmstrip, and providing a plurality of registration-tension assemblies carried by the substrate, the registration-tension assemblies each at least including a registration pin member having a registration pin sized for a non-interference fit with filmstrip perforations and a tension pin member having a tension pin sized for a non-interference fit with filmstrip perforations.
The method also includes the steps of providing a registration mode to engage and register a filmstrip by resting an edge of one perforation of the filmstrip against the side of an inserted registration pin, and placing the filmstrip in tension by pulling the filmstrip via a tension pin inserted in another perforation in the filmstrip, in a direction substantially parallel to the direction of filmstrip transport and away from the registration pin, and providing a load mode to load the registration and tension pins into prospective perforations by moving the tension pin in a direction substantially parallel to the direction of filmstrip transport and toward the registration pin until the registration and tension pins achieve a distance therebetween permitting a non-interference fit into two filmstrip perforations.